Well logging instruments that utilize radiation generators, such as sealed-tube neutron generators, have proven incredibly useful in oil formation evaluation. Such a neutron generator may include an ion source or ionizer and a target. An electric field, which is applied within the neutron tube, accelerates ions generated by the ion source as an ion beam toward an appropriate target at a speed sufficient such that, when the ions are stopped by the target, fusion neutrons are generated and irradiate the formation into which the neutron generator is placed. The neutrons interact with elements in the formation, and those interactions can be detected and analyzed in order to determine characteristics of interest about the formation.
Traditional neutron generators tightly focus the ion beam to help reduce a number of undesirable effects that can shorten their lifetime. However, a tightly focused ion beam may cause the formation of an area or hole in the target depleted in the reactants used for producing fusion neutrons. This can lower the neutron output of the neutron generator, or even lead to failure of the neutron generator.
Another type of radiation generator is an x-ray generator, and includes an electron source and a target. An electric field applied in the x-ray tube accelerates electrons emitted by the electron source as an electron beam toward the target at a speed sufficient such that, when the electrons are stopped by the target, Bremsstrahlung x-rays are released.
Traditional x-ray generators tightly focus their electron beams, which can cause a hole to be burned in the target. This can lower the x-ray output of the x-ray generator, or even lead to failure.
Thus, radiation generators capable of mitigating these undesirable effects of tightly focused beams are desired.